Island Morning Glory
There aren't many vines native to California, and few are truly evergreen. Fewer still are both evergreen and vigorous enough to cover a good-sized arbor or trellis. Calystegia macrostegia (coastal or island morning glory) is one that really fills the bill. It may drop leaves in summer if grown dry, but a little supplemental water or summer fog is enough to keep it green and growing near the coast. And vigorous? You may have to hold it back. Widely flaring flowers of Calystegia macrostegia tend to close by late afternoon or on cloudy days. The species is
